A substrate, such as a semiconductor wafer, can be moved from one location to another location by a variety of methods. For example, mechanical rollers are typically used in semiconductor manufacturing systems to move the substrate within the system. Specifically, a substrate may be placed between rollers such that the tapered surfaces of the rollers catch the edges of the substrate. To move the substrate, the rollers rotate to push the substrate towards a direction of the rotation. The problem with rollers, and other mechanical devices, is that the mechanisms associated with the rollers can be complicated. Furthermore, rollers must make contact with the substrate to move the substrate. Such contact can exert considerable stress on the substrate, which may lead to the degradation of the substrate.
Water also has been used to move a substrate. For example, the substrate can be placed in a flow of water to move the substrate in a direction of the flow. The problem with using water to transport the substrate is that the substrate can sink and stick to a bottom surface, thereby impeding transport of the substrate. When the substrate is stuck to a surface, the substrate cannot easily be dislodged. The substrate sinks to the bottom because water cannot support the substrate. Accordingly, the use of water to transport the substrate can be unreliable and the substrate is prone to being stuck at the bottom.
In view of the foregoing, there is a need to provide a simpler and more reliable method and apparatus to transport the substrate.